I've been wondering lately. As we know, the Republic's military, initially composed of judicial (planetary defence?) forces, underwent centralisation, standardisation, and of course, an almost unimaginable expansion. In universe, I believe around millions of clone troopers were manufactured, trained, and served in the army and no doubt millions more served as navy personnel. (the exact number eludes me, but I think billions wouldn't be too far fetched considering the scale of Star Wars)
It seems that most senior officers in the Republic's Army and Navy were still humans or at least non-clones. I believe most if not all the of the Republic's captains and admirals shown in the Clone Wars show were humans from Tarkin to Kilian to Yularen. Of course, in the army, there was Colonel and later Brigadier General Meebur Gascon.
Since the army and navy expanded greatly, so would the officer corps in both branches as well. Though clones could hold a rank as high as Marshal, it seems that most of them still fell under the authority of a human or alien commander.
This leads me to my main question, though most of the senior officers shown in the Clone Wars were, well... senior, do we know anything about newly appointed non-clone officers in the Republic's military? Do we know anything about their appointments? How they were appointed? Obviously some officers graduated from places such as Carida Academy, but at the scale and speed of the Republic's expansion, would such academies be able to provide enough officers in time to function as subordinates, executives, ship commanders, regimental commanders, and so on and so forth? Are there any clear cases of civilians, politicians, people with no military experience, being appointed as officers directly into the Republic's military due to the need for organic (non-clone) senior officers?
The Republic, as we know, was quite corrupt, perhaps excessively so. It would not be implausible, I think, that patronage would be one of the recognised paths to a commission into the military. Using a historical analogy, we know that in the American Civil War, quite a few field officers: majors, lieutenant colonels, and colonels were commissioned outright by the state to serve as volunteer officers. One of the more notable ones is the famous Colonel Chamberlain who was a professor of rhetoric at Bowdoin College and turned down a colonel's commission and instead became a lieutenant colonel first as he thought himself too inexperienced for the job. Generals Benjamin Butler, John McClernand, and Nathaniel P. Banks were all commissioned as generals (of varying grades) without prior or at least extensive military experience (and only in the state militia for Butler). While obviously Star Wars is not the real world, there are still several notable parallels between the Republic and many historical and even modern governments, one of them being patronage... and in a corrupt Republic, perhaps that mattered most...
I would also ask the same question for the CIS, though I actually believe that appointing organic officers in the CIS is far more likely... as though there were indeed tactical droid generals, organic officers still seemed to hold the highest positions as generals, admirals, ship captains, and I believe in some parts of the CIS military, there were non-droid units where humans and aliens occupied all the ranks from the lowest to the highest.
I would appreciate corrections for any possible misunderstanding I may have about the lore.
Edit: Excluding the Jedi who were appointed officers, by the way.